Ultrasonic Drilling Research Articles

Research on Chip Removal Performance of Rotary Percussive Ultrasonic Drill for Planetary Rock Sampling

The objective of the kinematic model of rock chips is to examine the impact of the driving parameters of drilling tools on the effective chip removal speed, with a view to analyze the chip removal performance of rotary percussion ultrasonic drilling. The discrete element numerical simulation method, EDEM-2022 simulation software, was employed to establish a simulation model, match the simulation parameters, and conduct a simulation study of chip removal under the action of rotary percussion. This was performed to analyze the influence of the driving parameters on the chip conveying process. In order to ascertain the order of parameters affecting the degree of conveyance rate as well as the optimal driving parameters, orthogonal experiments were designed based on Taguchi’s experimental analysis method.

Deep learning-based temperature prediction during rotary ultrasonic bone drilling

Bone drilling is a common but critical medical procedure in orthopedic surgeries used to treat fractured bones. During this procedure, the temperature of the bone increases due to generation of frictional energy. Temperature control has been a major challenge in bone drilling since its foundation. If this temperature increases over 47°C for 1 min, then it can result in permanent bone damage. To control the temperature elevation this study proposes a deep learning-based robust predictive model which has been trained and tested on data from pig bones. Excessive in-house testing has been done on pig femur bones to gather data and verify the results. Rotary ultrasonic bone drilling was the machining process used for drilling. Four independent variables which were rotational speed, feed rate, abrasive grit size, and vibrational ultrasonic power were varied and the temperature for each set of values was recorded. Multiple deep learning models were made and were compared on different error metrics. It was found that convolutional neural network 1D gave the least error over other models. The error generated by deep learning models was less than mathematical and experimental models.

Research on the key techniques of composite processing of EDM and vibration ultrasonic drilling

PurposeUtilizing electrical discharge machining (EDM) to process micro-holes in superalloys may lead to the formation of remelting layers and micro-cracks on the machined surface. This work proposes a method of composite processing of EDM and ultrasonic vibration drilling for machining precision micro-holes in complex positions of superalloys.Design/methodology/approachA six-axis computer numerical control (CNC) machine tool was developed, whose software control system adopted a real-time control architecture that integrates electrical discharge and ultrasonic vibration drilling. Among them, the CNC system software was developed based on Windows + RTX architecture, which could process the real-time processing state received by the hardware terminal and adjust the processing state. Based on the SoC (System on Chip) technology, an architecture for a pulse generator was developed. The circuit of the pulse generator was designed and implemented. Additionally, a composite mechanical system was engineered for both drilling and EDM. Two sets of control boards were designed for the hardware terminal. One set was the EDM discharge control board, which detected the discharge state and provided the pulse waveform for turning on the transistor. The other was a relay control card based on STM32, which could meet the switch between EDM and ultrasonic vibration, and used the Modbus protocol to communicate with the machining control software. FindingsThe mechanical structure of the designed composite machine tool can effectively avoid interference between the EDM spindle and the drilling spindle. The removal rate of the remelting layer on 1.5 mm single crystal superalloys after composite processing can reach over 90%. The average processing time per millimeter was 55 s, and the measured inner surface roughness of the hole was less than 1.6 µm, which realized the micro-hole machining without remelting layer, heat affected zone and micro-cracks in the single crystal superalloy.Originality/valueThe test results proved that the key techniques developed in this paper were suite for micro-hole machining of special materials.

Simulation of the impact of an ultrasonic drill as a composition of a robotic platform for investigation of soil on celestial bodies

The article discusses the theoretical issues of developing an ultrasonic drill for drilling soil on celestial bodies as part of a robotic platform and formulates the tasks of its control. The specifics of using the drill require a wide temperature range during operation, low energy consumption, an efficient operating cycle and the requirement to ensure the preservation of the structure and composition of the soil when exposed to the tool. One of the promising areas of development is devices with vibration decoupling from the ground by ultrasound due to the transformation of ultrasonic vibrations into repeated impacts of sound frequency using a specially introduced “free” body between the ultrasonic and impact parts of the drill (bit). This allows continuous drilling regardless of the condition of the impact bit, including jamming. The purpose of the work is to select the most effective drill design and compile a mathematical model that provides simulation modeling. Materials and methods. Technical solutions of both domestic and foreign authors were considered, and a prototype was selected. Theoretical works were analyzed and it was found that the materials presented in them do not contain detailed mathematical models necessary for simulation modeling at the stage of design and optimization of the structure. In the theoretical part of the article, mathematical models are proposed, obtained on the basis of equivalent parameters found from a distributed description of the drill design elements. Methods of mathematical physics, classical mechanics and similarity theory were used. The results are that two alternative mathematical models are developed. One of the models has a continuous description with a significantly nonlinear rigidity of the “wall” upon impact, while the impact motion is considered as a type of self-oscillation. The second model is based on the theory of impact. Conclusion. A parametric study was carried out and the dependences of the oscillation frequency of a free body on the size of the impact gap, body mass and amplitude of oscillations of the concentrator, etc. were obtained. The considered models can be used for simulation modeling when developing a drill design. The tasks of controlling a robotic drilling platform are formulated from the position of ensuring the operability of the drill when drilling various soils.

Experimental evaluation and optimization of parameters affecting delamination, geometrical tolerance and surface roughness in ultrasonic drilling of 3D-Printed PLA thermoplastic

Ultrasonic drilling is a suitable process to enhance the generated surfaces by additive manufacturing. In this study, polylactic acid was selected as the workpiece. The examination parameters were thrust force, delamination, geometrical tolerance, chip adhesion, hole wall morphology and surface roughness. It was explained that the harmonic movement of drill bit in ultrasonic drilling reduced thrust force, delamination, circularity, cylindricality and surface roughness up to 14.5%, 3.7%, 44%, 38%, 20% respectively and removed chip adhesion. Furthermore, number of end-mill flutes was examined and observed that 4-flutes compared to 2-flutes induced reduction in thrust force, delamination, circularity, cylindricality and surface roughness up to 15.2%, 2%, 7.5%, 18.9%, 12.5% respectively. Besides, analysis of variance was established to determine the significant parameters. Finally, non-dominated sorting genetic algorithm-II technique was implemented in order to carry out multi-response optimization.

Investigating mechanisms of debris removal in ultrasonic vibration-assisted EDM drilling

In traditional electrical discharge machining (EDM) of micro-holes, the debris removal becomes increasingly challenging as hole depth increases, significantly affecting the machining of difficult-to-machine materials. To address this issue,we first developed a micro-hole gap flow field model for a novel longitudinal–torsional ultrasonic vibration (LTV) electrode EDM drilling method. We analyzed the effects of three types of electrodes — rotation electrodes, longitudinal ultrasonic vibration (LUV) electrodes, and LTV electrodes — on the flow velocity in the micro-hole interstitial flow field. Next, we simulated the motion of fluid and debris in the interstitial flow field of micro-holes, theoretically verifying the advantage of electrode ultrasonic vibration in enhancing debris removal efficiency. Additionally, we observed the electrode tip morphology, the elemental composition on the electrode surface, and the morphology of the micro-hole inlet/outlet and inner wall to further elucidate the debris removal mechanism and confirm the superior drilling performance of the ultrasonic vibration electrodes. At an optimal ultrasonic amplitude (AL=4μm), the LUV electrode demonstrated improved consistency in the micro-hole inlet/outlet and achieved a micro-hole taper of 0.014°. The material removal rate (MRR) using the LTV electrode reached 5.14 × 105μm3/s, nearly 1.5 times higher rotation electrode. This method successfully produced a positively tapered hole suitable for injector nozzles.

Hole-exit defect formation during traditional and ultrasonic vibration-assisted drilling of C/SiC composites

Hole-exit defect formation during traditional and ultrasonic vibration-assisted drilling of C/SiC composites

Processing parameter effect, formation mechanism and inhibition method of micro-hole exit defects in rotary ultrasonic pecking drilling of SiCf/SiC composites

High brittleness and anisotropy of ceramic matrix composites lead to great challenges for micro-hole machining. Micro-holes with large depth-to-diameter ratio (10:1) of SiCf/SiC composites were machined by rotary ultrasonic pecking drilling process. Based on the mechanical theory and structural characteristics of SiCf/SiC, a critical thrust force model was established. The effects of processing parameters on machining accuracy and machining quality of micro-hole exits were analyzed and parameters were optimized. The formation mechanism of exit defects includes interfacial debonding, fiber bending and matrix fracture. A method based on the surface morphology to inhibit exit defects by increasing the support stiffness of the material was proposed, under which the exit roundness all reached IT8 level and chipping factors decreased by 53 %–67 %, and only a small amount of chipping and micro-cracks was at the exit. The proactive control of micro-hole exit defects was realized, and a better machining quality was obtained.

Critical force of separation effect behaviors in rotary ultrasonic drilling for SiC

Critical force of separation effect behaviors in rotary ultrasonic drilling for SiC

Improvement of drilled holes quality by voice-activated ultrasonic vibration assisted drilling process of different orientation

Ultrasonic drilling enables drilling in difficult-to-machine materials, including ceramics and composites, with greater accuracy and precision. The localized and controlled energy application of ultrasonic frequency minimizes the risk of material fracture, cracks, or delamination. This capability ensures that the drilled hole maintains its intended dimensions, shape, and integrity, resulting in improved hole accuracy and overall drilled hole condition. Ultrasonic drilling is an advanced machining technique that utilizes high-frequency vibrations to improve the drilling process. In this designed voice-activated module, electrical energy has been converted into mechanical vibrations through piezoelectric transducers, generating ultrasonic waves in the range of 20 kHz to 80 kHz. Experiments has been conducted considering different process parameters with the changing different orientations of the emitters-horizontal and vertical positions and comparison was done with no vibration conditions. It has been observed that with the application ultrasonic vibration frequency the surface roughness improved by 45% in horizontal position, 28% in vertical position compared with no vibration conditions-conventional techniques. It has also been observed that the circularity index of the drilled holes also improved by 31% for horizontal and 7.6% for vertical position.

Simulation and experimental research on longitudinal-torsional ultrasonic vibration drilling of CFRP/Ti laminates

Carbon fiber reinforced polymer (CFRP) and titanium alloy (Ti) laminated materials are extensively employed as primary load-bearing structures in aerospace engineering due to their exceptional characteristics. During the drilling process of CFRP/Ti laminates, issues like delamination and burr formation significantly impede the overall performance of these laminates. The finite element simulation was carried out to address above challenges using longitudinal-torsional ultrasonic vibration drilling (LT-UVD) of CFRP/Ti laminates. A three-dimensional solid model of CFRP/Ti laminates was developed using the ABAQUS custom VUMAT subroutine interface. A cohesive element was skillfully incorporated into the model to simulate delamination defects in the CFRP material effectively and to elucidate the material damage trends and stress distribution throughout the drilling process of laminated materials. The results obtained from the finite element simulation are meticulously compared with experimental data, revealing a consistent trend in the axial force curve. The simulated axial force’s peak value is 14.45% lower than the peak value obtained from experimental observations. The findings of this research substantiate the efficacy of the developed finite element model for LT-UVD of CFRP/Ti. The model successfully predicted the changing trend of axial force and layered defects during the drilling process. Moreover, it provides a visually intuitive instantaneous cutting state and stress distribution, imparting valuable insights into the intricate drilling mechanisms involved in CFRP/Ti laminates.

Machinability of submillimeter holes in ceramic matrix composites by high-frequency ultrasonic vibration-assisted drilling

Ceramic matrix composites (CMCs) are highly promising for the hot components of the high thrust-to-weight ratio aeroengines because of their excellent high-temperature resistance and lightweight. Submillimeter cooling holes are necessary cooling structures for the extremely high working temperature of a CMCs hot component. However, CMCs are hard, brittle, and poorly conductive. Current machining is trapped in severe tool wear, poor hole quality, and low efficiency in machining such small size holes. This paper proposes high-frequency ultrasonic vibration-assisted drilling (UAD) to machine submillimeter holes of CMCs. It reveals that increasing vibration frequency during machining can enlarge the cutting edge's effective rake angle and reduce drilling forces. Correspondingly, the tool life and hole quality are improved. The machinability of high-frequency UAD is rationalized by both theoretical analysis and experiments. Results show that compared with low-frequency UAD and Conventional drilling (CD), the drilling force in high-frequency UAD is reduced by 47 % and 81 %, the tool life is more than three times, and the hole quality is improved by 12 % and 35 %, respectively. Therefore, the study paved the way for the machining of submillimeter cooling holes in CMCs, which is important to the industrial application of CMCs.

Influence of transversal vibration on cutting performance and surface integrity during ultrasonic peening drilling of Al-Li alloys

Advanced hole-making process is of great importance to enhance the fatigue performance of Al-Li alloy part in aviation industry. Ultrasonic peening drilling (UPD), in which an ultrasonic transversal vibration is applied to the cutting tools, is a recently proposed hole-making method that integrates precision-machining and surface strengthening by single-shot operation. In the study, kinematics, material removal mechanism and strengthening mechanism for UPD of Al-Li alloy by helical fluted reamers are analyzed. The effect of transversal vibration on the cutting performance and surface integrity is studied through comparative experiments between UPD and conventional drilling (CD) of Al-Li alloy holes. The experimental results show that UPD exhibits superior cutting performance with a maximum reduction of 52.6% in thrust force and 52.3% in torque, respectively, compared to CD. Moreover, narrower dimensional tolerance is obtained in UPD due to the reduced transversal force and improved machining stability. Additionally, deeper plastic deformation, higher surface microhardness and residual compressive stress of machined holes are obtained by UPD. The electron back-scattered diffraction (EBSD) analysis confirms that deeper machined affect area and grain refinement are realized in UPD. Therefore, the results indicate that UPD is a feasible method for achieving high-precision and strengthened holes for Al-Li alloy.

Understanding the mechanism of ultrasonic vibration-assisted drilling (UVAD) for micro-hole formation on silicon wafers using numerical and analytical techniques

Understanding the mechanism of ultrasonic vibration-assisted drilling (UVAD) for micro-hole formation on silicon wafers using numerical and analytical techniques

High-efficiency ultrasonic assisted drilling of CFRP/Ti stacks under non-separation type and dry conditions

High-efficiency ultrasonic assisted drilling of CFRP/Ti stacks under non-separation type and dry conditions

Experimental Study and Application of Ultrasonic Vibration Technology in Enhancing Deep-Hole Drilling Tool Performance

This study delves into the application of ultrasonic vibration technology in enhancing the performance of deep-hole drilling tools and its consequential effects on the machining process. By integrating ultrasonic vibrations, this research aims to unveil how such vibrations refine the interaction between the tool and material during deep-hole drilling, thereby achieving a reduction in frictional forces, a decrease in machining temperatures, an increase in the efficacy of cutting fluids, and an improvement in chip removal. The experimentation employed an array of tools, including internally cooled welding-style end-face cutters, multi-edged BTA, and single-edged BTA, to investigate the performance variations under different machining parameter configurations. The findings indicate that, compared to conventional drilling methods, ultrasonic vibration-assisted deep-hole drilling substantially elevates machining efficiency, enhances hole wall quality, and significantly reduces tool wear while prolonging tool life.

Ultrasonic tool shank with multiple vibration mode for micro-nano drilling: Design, optimization and experiment

The machining effects of hole drilling is limited by merely changing the amplitude. Adjusting ultrasonic vibration frequency to expand the matching range of machining parameters optimization is necessary to improve hole drilling effects. Therefore, the design, optimization, and experiment evaluation for a novel integrated, fined, low-cost dual-frequency ultrasonic tool shank is proposed, which can work in three vibration modes for micro-nano precision drilling. The principle of the dual-frequency ultrasonic transducer is introduced. The electro-mechanical equivalent circuit model with step horn is applied to study the dual-frequency characteristics. The transducer displacement equation model based on the wave equation theory is deduced to find the shared vibration node of the first and third frequency. Sensitivity analysis by equivalent circuit model and Finite element method (FEM) simulation of the key parameter is both conducted to optimize ultrasonic transducer geometry dimension. The vibration node of mounting flange is specified in an identical position for the dual vibration modes. A prototype of ultrasonic tool shank is fabricated and evaluated in experiments. It demonstrates that the dual working frequency of the ultrasonic transducer is 34.9 kHz and 104.5 kHz in the first and third mode resonant vibration, which is benefit to the low and high frequency drilling. Three working modes of the low, high, and coupling frequency vibration is measured by a self-developed ultrasonic generator. When 40 V voltage is excited, the vibration amplitudes of the low and high frequency are 17.8 µm, and 9.3 µm, respectively, which can meet with the drilling requirement. Moreover, the coupling vibration with the low and high mode are excited simultaneously, and the motion trajectory of the coupling vibration is observed in a “M” shape, which is a novel trajectory for the precision micro-nano drilling. Micro drilling experiments show that the 35 kHz ultrasonic vibration drilling can achieve better machining effect than conventional drilling (CD). The 105 kHz ultrasonic drilling outperforms the CD, 35 kHz and coupling ultrasonic drilling at cutting force reduction. The coupling ultrasonic vibration drilling achieves the lowest chipping diameter. It is to be noted that the 105 kHz-8 µm produce the fined smoothly surface. The 35 kHz, 105 kHz and coupling ultrasonic drilling can produce better surface micro morphology with less quantity and size of craters than that of CD.

Introducing transversal vibration in twist drilling: Material removal mechanisms and surface integrity

In twist drilling, severe extrusion is unavoidable at the chisel edge zone and results in high thrust force and poor surface integrity. Traditional axial vibration-assisted twist drilling only modifies the material removed from the continuous extrusion to the interrupted extrusion for the chisel edge centre, and must satisfy the chip-breaking conditions to ensure that the cutting edge is periodically separated from the workpiece. Hence, transversal vibration, has been introduced in twist drilling to overcome the severe extrusion behaviour of the chisel edges of the twist drills, referred to as ultrasonic transversal vibration-assisted drilling (UTVD). Theoretical models revealed that the material removal behaviour of the chisel edge centre changed from extrusion in CD to cutting in UTVD. Experiments were performed on UTVD of Ti-6Al-4V to confirm the feasibility with this novel method. The results indicated that transverse vibration significantly affected the thrust force and torque, and the maximum decline was 29.4% and 31.5%, respectively, compared with CD. Generated chips verified the material removal behaviour of the chisel edge centre zone changed from extrusion in CD to cutting in UTVD. Therefore, the hole quality and surface integrity were improved significantly by UTVD. Deeper plastic deformation (∼2.5 times), higher surface microhardness and compressive residual stress were realised using UTVD. This study enhanced the understanding of material removal and formation mechanisms of the surface and subsurface in UTVD, thereby providing a novel method and theoretical basis for the high-performance twist drilling of difficult-to-cut alloys.

Enhancing engagement behavior in small-diameter deep drilling through ultrasonic vibration-assisted drilling and quantitative evaluation of hole dimensions

Enhancing engagement behavior in small-diameter deep drilling through ultrasonic vibration-assisted drilling and quantitative evaluation of hole dimensions

Об одном способе ультразвукового бурения скважин для забора грунта на небесных телах

The article discusses technical and theoretical issues in the development of an ultrasonic drill for drilling soil on celestial bodies. The specific use of the drill requires low energy consumption, an efficient operating cycle and a wide temperature range during operation. One of the promising areas of development is devices that have vibration decoupling from the ground due to the transformation of ultrasonic vibrations into repeated shocks of sound frequency through a specially introduced “free” body between the ultrasonic and impact parts of the device. This allows you to maintain the functionality of the device and carry out drilling regardless of the state of the impact bit, including even its temporary jamming. The main technical solutions of both domestic and foreign authors are considered, an analysis is made and design schemes, operating conditions, capabilities and limitations are evaluated. A number of theoretical works were also analyzed and it was found that the materials presented in them do not contain detailed mathematical models necessary for simulation modeling at the stage of design and optimization of the structure. The theoretical part of the article considers a lumped mathematical model obtained on the basis of equivalent parameters obtained from a distributed description of the drill design elements in numerical calculation systems. The equations of mathematical physics, classical mechanics, elements of impact theory and similarity theory were used. A parametric study was carried out and, in particular, the dependences of the oscillation frequency of a free body on the size of the impact gap, body mass and the amplitude of oscillations of the concentrator were obtained. The considered model can be used for simulation modeling when developing a drill design.